Strength development and lime reaction in mortars for repairing historic masonries

In this research, restoration mortars with analogous chemical composition of binders, aggregates and mineral additions, as they derive from the study of historic mortars, were evaluated regarding the strength development and the lime reaction, up to 15 months of curing. For this purpose several mixtures were tested in laboratory regarding their chemical and mechanical characteristics. The obtained results show that most of them present a slow rate of chemical and mechanical evolution, with the exception of hydraulic lime mortar and mortar with lime putty-natural pozzolanic addition. The best mechanical behavior was observed in mortars with lime powder and lime powder-artificial pozzolanic addition. These materials present also a low ratio of compressive to flexural strength (fc/ff). Further investigations on these materials would determine the time where their chemical and mechanical characteristics become stable. Only at that time, it would be possible to compare the compatibility characteristics of the restoration mortars with those employed in the past.